In mass manufacturing and mass assembly processes, various items, such like substantially planar-shaped or disc-like items, typically provided in a stack of items, have to be singulated or separated from each other in order to allow for a proper and precise assembling of the item with other objects to be mutually assembled. Depending on the geometry of the items, their separation is sometimes tricky and cumbersome. For instance with rather tiny, low weight disc-like or planar shaped items, which may also be arched or curved, it is rather elaborate to precisely separate a single item form a stack of items that e.g. extends in an axial direction.
Gripping for instance of an uppermost item e.g. by means of a suction cup requires to bring the suction cup in direction contact with the respective item. This requires that the suction cup has to be positioned in various axial height above the stack. Here, the height varies with stack size and the number of items of the respective stack. Especially when the items are of non-planar geometry, arranging numerous items on top of each other in a stack may eventually lead to a jamming or tilting of items. When gripping the uppermost item of the stack, the suction cup may get in direct contact with the respective item. As a consequence, the entire stack may become subject to axial compression as the suction cup hits or engages with the uppermost item. Due to such an axial compression, various items of the stack may get caught or may mutually catch, their separation may therefore become rather crucial and complex.
Taking or gripping of the uppermost item from a vertically or axially extending stack of items also generally requires a respective axial height adjustment between the stack of items and the suction cup. By successively separating items from the stack of items, the total axial or vertical height of the stack successively reduces and therefore requires a rather delicate and precise positioning of the suction cup for not exerting significant axial pressure to the stack.
Moreover, a contact-based gripping of an item may also lead to significant abrasion or wear of the items and their surface.
Additionally, a sensor-based positioning of at least a suction cup or some other gripping tool relative to a stack-supporting carrier unit may require implementation of comprehensive sensor equipment, which is rather expensive and which may further limit the cycle time of an assembly- or manufacturing process.
Moreover, if the items to be separated are subject to geometric tolerances, a sensor-based gripping and separation as well as a well-defined mutual positioning and alignment of a stack-supporting carrier unit and a suction cup is rather susceptible to malfunction and may therefore lack sufficient reliability.
It is therefore an object of the present invention to provide an improved separating device, which is highly reliable and which provides a well-defined and precise separation of a single item from a stack of items. The separating device should comprise a rather simple structure and should support rather short cycle times for a mass assembly or mass manufacturing process. Additionally, the separating device should avoid or reduce exertion of axial pressure to the stack and should further provide an operation mode, which is rather independent of the actual height of the stack. Additionally, a respective method for separating an item from a stack of items should be provided, which is highly reliable and by way of which a well-defined successive separation of single items from a stack of items can be provided.